In consideration of non-consumable melting systems for melting a variety of materials and also heating applications, the plasma torch has come to be favored for many special applications where relatively high temperature, flexible heating systems are required. Such applications include metal melting, powder production, waste incineration, and many other applications requiring a high temperature, non-contaminating electrical heat source.
The plasma torch is also deemed a desirable heat source because of the relatively long arcs that can be generated as compared to other arcing systems using considerably shorter arcs. In such other systems, shorter arcs are not useful for many applications and do not have the precision or directional capabilities found to be characteristics of the more advanced plasma torch designs.
One major disadvantage of the transferred arc plasma torch is a problem referred to as double arcing which is caused when the nozzle of the torch strikes a grounded object, causing an arc from the nozzle to the object. Such an arc may cause extreme damage to the nozzle or complete destruction of the nozzle if prolonged arcing occurs. A need, therefore, exists for an improved design of a plasma torch having the capability of avoiding the problem of double arcing mentioned above.